JPS63241832A - Temperature sensor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a temperature sensor that detects temperature, and particularly to a temperature sensor using a shape memory alloy or the like as a sensor element.

[Conventional technology]

When a shape memory alloy reaches a transformation temperature, it changes to its memorized shape, and thus temperature sensors have been developed that utilize this shape change to operate electrical contacts.

However, conventional temperature sensors act only on opening and closing of electrical contacts, and no one has been developed that operates a limit switch or resets it after activation. For this reason, there are problems such as it is difficult to control the change in shape due to metamorphosis, and it takes time and effort to restore the original shape.

Therefore, this invention uses a shape memory alloy as a sensor element to turn on a limit switch.

The object of the present invention is to provide a temperature sensor that can be turned off.

[Means for solving problems]

In order to achieve the above object, the present invention includes a sensor element whose shape changes to have a spring force with a predetermined temperature as a transformation point, and a sensor element which engages with this sensor element and is displaced to follow the shape change of the sensor element. A cantilever lever, a spring-like switch member that is attached to the limit switch so as to receive the displacement of the cantilever lever, and changes to actuate the limit switch in response to the displacement; It is characterized by comprising a reset member that restores the shape.

[Effect]

When the temperature exceeds the transformation temperature of the shape memory alloy or the like, the sensor element changes its shape, and the switch member opens or opens the electric contact of the limit switch via the lever to detect the temperature. The sensor element has a spring force due to its shape change, which counterbalances the spring force of the switch member, thereby maintaining the operating state of the limit switch. The reset member acts when restoring the sensor element.

〔Example〕

Hereinafter, the present invention will be specifically described with reference to illustrative embodiments.

FIG. 1 is a sectional view of one embodiment of the present invention, and FIG. 2 is a sectional view showing its operation. A limit switch 2 and a coil-shaped sensor element 3 are provided within a case 1. The sensor element 3 is formed by winding a wire made of a shape memory alloy into a coil spring shape, and its lower end is fixed to the case 1, and its upper end is fixed to the lever 4.
It is hung on the tip side. This sensor element 3 is made of an alloy whose transformation point is a predetermined temperature (for example, 80° C.), and is memorized so that when the temperature reaches the transformation point or higher, the shape changes in a direction in which the coil length is reduced. Therefore, the sensor element 3 has a spring force due to its shape change. The base end of the lever 4 is rotatably supported by the case 1, and an insertion hole 4a through which a shaft of a reset member 5 (described later) is inserted is formed in the intermediate portion thereof. Since the upper end of the sensor element 3 is hooked to the distal end of the lever 4, when the sensor element 3 changes shape in the direction in which the coil length is shortened above the transformation point, the sensor element 3 moves counterclockwise around the base end. Displace as if rotating.

The limit switch 2 has an internal electrical contact (not shown)
A button 6 is provided on the upper end surface for switching operation, and a button 6 for opening and closing this electrical contact is attached to the upper end surface so as to be movable up and down. A switch member 7 made of a spring plate or a spring bar is attached to the upper end surface of the limit switch 2.
The switch member 7 extends obliquely upward so that its upper end is close to the lower surface of the lever 4. The switch member 7 does not come into contact with the button 6 under normal conditions, but when the lever 4 is displaced downward due to a change in the shape of the sensor element 3, it bends under the pressure of the lever 4 and presses the button 6. This activates the limit switch 2.

The reset member 5 is attached to the case 1 so as to be able to move up and down, and has a shaft portion 5a that is inserted into the insertion hole 4a of the lever 4, and a shaft portion 5a that is attached to the upper end of the shaft portion 5a and extends outward from the case 1. It is equipped with a knob 8 that has been taken out. As shown in FIG. 1 (C>), this shaft portion 5a has a counter spring 1 biased in a direction opposite to the direction in which the sensor element 3 deforms (shrinks) when heated above the transformation temperature.
1 may be provided. In this case, there is no need to lift the knob 8 of the reset member 5 to reset the temperature below the transformation temperature. Further, the lower end of the shaft portion 5a has an insertion hole 4 for the lever 4.
In order to prevent removal from the insertion hole 4a, it is formed into a flange shape with a larger diameter than the insertion hole 4a. In the figure, numerals 9 and 9 are lead wires, and numerals 10 and 10 are terminals, which are installed to connect the limit switch 2 to an alarm device such as a buzzer (not shown).

Next, the operation of the above embodiment will be explained.

FIG. 1(A) shows the state before temperature detection, in which the lever 4 and the switch member 7 are separated, and the switch member 7 and the button 6 are also separated, so that the limit switch 2 cannot be operated. When the temperature reaches the transformation point or higher of the sensor element 3, the shape of the sensor element 3 changes in a direction in which the coil length thereof contracts, so that the lever 4 changes downward.

As a result, the lever 4 presses the upper end of the switch member 7 and bends it in the same direction, so the switch member 7 presses the button 6, thereby operating the limit switch 2. let

While the temperature is rising, the sensor element 3 changes shape so as to roughly contract, but is stopped by the reaction force of the spring-like switch member 7 in contact with the button 6.

Therefore, above the transformation temperature, the reaction force of the switch member 7 always acts on the sensor element 3, but due to the change in shape, the sensor element 3 has a spring force, and this spring force and the spring force of the switch member 7 Since these are counterbalanced and are in an equilibrium state, the state in which the button 6 is pressed continues.

The two-dot chain line in FIG. 1 (8) indicates the position of the lever 4 when the sensor element 3 changes its shape completely, and changes like this when the reaction force from the switch member 7 does not act. Therefore, the difference in height between the solid line state of the lever 4 and the two-dot chain line state is the reaction force exerted by the switch member 7.

This state of pressing the switch member 7 continues even when the temperature drops below the transformation point.Next, in order to reset this, lift the knob 8 of the reset member 5 and turn the shaft portion 5a. This is done by raising it. Due to this rise, the lower end of the shaft 5a pushes up the lever 4, so the lever 4
The sensor element 3, whose upper end is latched, undergoes plastic deformation and the coil length is extended, and the switch member 7, which had been pressed by the lever 4, is separated from the button 6 by its spring force, and the limit switch 2 is reset. . Since the reset member 5 has the knob 8 pushed out from the case 1, it is possible to check the operation of the limit switch 2 by pushing the knob 8.

By the way, the switch member 7 has a spring force that is strong enough to allow the sensor element 3 made of a shape memory alloy to deform to its original shape (stretched state) below the transformation temperature, and which occurs when heated above the transformation temperature. The restoring force may be smaller than the restoring force. In this case, even if the temperature is below the transformation temperature, there is no need to take the trouble to lift the knob 8 of the reset member 5 to reset it, and the reset member 5 is used to check the operation of the limit switch 2 and to force a reset when the switch member 7 is in a jam state. It functions as a means.

Next, a second embodiment of the present invention will be described.

FIG. 2 is a sectional view of the second embodiment, in which the same elements as in the above embodiment are designated by the same reference numerals.

In this embodiment, the sensor element 3 is made of a shape memory alloy shaped like a leaf spring bent in the shape of a square.

In the sensor element 3, the lower bent blade 3a is connected to the case 1.
The upper bent blade 3b is attached to the upper surface of the lever 4 with screws. Moreover, the shape is memorized so that the bending angle θ of the two sides 3a and 3b becomes small at temperatures above the transformation point, and when the temperature exceeds the transformation point, the switch member 7 deforms in the direction of the arrow in the figure. presses button 6 and the limit switch is activated. This state of pressing the switch member 7 continues even when the temperature drops below the transformation point.Next, in order to reset this, lift the knob 8 of the reset member 5 and turn the shaft portion 5a. This is done by raising it. Due to this rise, the lower end of the shaft 5a pushes up the lever 4, so the sensor element 3, which is attached so as to be in contact with the upper surface of the lever 4, undergoes plastic deformation, the bending angle θ increases, and the sensor element 3 is pressed by the lever 4. The switch member 7 is moved away from the button 6 by its spring force, and the limit switch 2 is reset. As explained in the first embodiment, the spring force of the switch member 7 is strong enough to deform the sensor element 3 to its initial shape (large bending angle) below the transformation temperature, and when heated above the transformation temperature. The restoring force may be smaller than the restoring force that occurs when the In this case, even if the temperature is below the transformation temperature, there is no need to lift up the knob 8 of the reset member 5 to reset the reset member 5.
It functions as a forced reset means in case something gets stuck.

Furthermore, as shown in FIG. 1(C), a counterspring 11 can also be applied. In this case, there is an advantage that there is no need to take the trouble to lift the knob 8 of the reset member 5 to reset the temperature below the transformation temperature. Although a shape memory alloy is used in this embodiment, a material such as a bimetal may also be used. In this case, as the temperature decreases, the bending angle θ increases due to the nature of the bimetal, so there is an advantage that there is no need to take the trouble of lifting the knob 8 of the reset member 5 to reset it. Therefore, in this case, the reset member 5 has the function of checking the operation of the limit switch 2 and as a forced reset means when the switch member 7 is caught.

The temperature sensors of the first and second embodiments described above are used, for example, by being attached to a bus duct in a factory. In other words, electric wire cables run inside the bus duct,
This detects the temperature abnormality when the wire cable generates heat due to some abnormality.

In this case, the output end of the limit switch 2 is connected to a control panel or the like in a monitoring room in the factory, and when the temperature sensor detects temperature abnormality, it issues an alarm to the control panel. In this invention, the sensor element 3 and the switch member 7 are counterbalanced and the limit switch 2 is activated until it is reset, so the alarm continues even if the temperature in the bus duct falls below the transformation temperature. Therefore, once an abnormality occurs, a warning is issued until the repair is completed, improving safety.

This invention is not limited to the above embodiments, and various modifications are possible.

For example, the sensor element is not limited to a shape memory alloy or a bimetal, but may be any material that causes a predetermined displacement when the transformation temperature is reached. Furthermore, the shape of the sensor element is not limited to that shown in the drawings.

〔Effect of the invention〕

As described above, this invention uses a shape memory alloy that changes so as to have a spring force as a sensor element, and provides a spring switch member that counterbalances this sensor element, so a limit switch can be incorporated. Since the shape of the sensor element is restored, it can be used repeatedly and can be checked.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the first embodiment of this invention, and FIG. 2 is a sectional view of the second embodiment.
It is a sectional view of an example. 2... Limit switch, 3... Sensor element, 4... Cantilever lever, 5... Reset member, 7...
...Switch parts.

Claims (1)

[Claims] 1. A sensor element whose shape changes to have a spring force with a predetermined temperature as a transformation point, and a cantilever that engages with this sensor element and displaces following the shape change of the sensor element. a lever; a spring-like switch member that is attached to the limit switch so as to receive displacement of the cantilever lever and that changes in response to the displacement to actuate the limit switch; and a spring-like switch member that engages with the cantilever lever and that is configured to actuate the sensor element; and a reset member that restores the shape of the temperature sensor. 2. The temperature sensor according to claim 1, wherein the sensor element is formed of a shape memory alloy wound into a coil. 3. The temperature sensor according to claim 1, wherein the sensor element is formed of a shape memory alloy or bimetal in the form of a leaf spring bent into a dogleg shape.